Method for the fractionation of mixtures containing dicyclopentadien and other materials



Jan. 25, 1955 2,700,643

M. R. KROGER METHOD FOR THE FRACTIONATION OF MIXTURES CONTAINING DICYCLOPENTADIEN AND OTHER MATERIALS Filed July 17, 1950 Jm eflwr MM AW M Further objects of the present invention may be seen from the following description of a preferred embodiment of the invention according to the accompanying drawing in which there is shown a plant designed according to the invention and adapted for the fractionation of dicyclo-pentadiene:

The feed stock, for instance the fore-runnings of the rectification of crude benzene, is drawn from the storage tank 1 to the mixer 2 where it is treated with lime or lime milk in order to absorb the acid constituents such as hydrocyanic acid, hydrogen sulphide, etc.

After the solid media and the watery solution have been removed. the stock is brought into a closed container 3 in which it is heated to a temperature of less than 100 C. without considerable evaporation so that any monocyclo-pentadiene in the stock may be converted to valuable dicyclo-pentadiene.

Coming from the heating container 3 the stock is then conveyed through the duct 4 into an evaporator 5 into which a duct 6 issues at the base a carrier gas, for instance cleaned coke oven gas in a finely divided state. After the carrier gas has passed through the contents of the container 5 it escapes, together with the evaporated constituents of the stock, through the duct 7 and then reaches either one or the other group of four adsorption containers 10, 11, 12, 13 or 14, 15, 16, 17, depending on the valves 8 or 9 used.

Both groups of adsorption containers are constructed indentically and are used in turn as described in the following. Inside the adsorption containers, which are preferably brick lined, an adsorption material such as activated coal is suitably arranged, for instance on hurdles. The gas enters the adsorption container at the top and flows through the adsorption materials from the top to the bottom. The bottom part of one adsorption container is connected with the top part of the next container by means of a pipe line 18 in which a cooler 19 is arranged controlled by two valves 20 and 21 fixed outside on both sides of the cooler. After the gases have passed one container they enter the next at the top.

' After the gas has passed the last adsorption container 13 or 17 of one or the other group of adsorption containers, it flows, being freed from its load, through the pipe line 25 controlled by the valves 23 or 24 into a scrubber 26 in which the gas is treated with concentrated sulphuric acid and if necessary with other materials suitable to extract certain constituents of the gas. After that the gas reaches the cooler 27 and from there fiows to a blower 28 which is connected with the duct 6 fixed at the evaporation container 5 by means of a duct 29 controlled by a valve 30.

It will be seen that the carrier gas is recirculated by means of the blower 28.

, The evaporator 5 is advantageously insulated against heat from the outside so that the evaporation can take place at possibly low temperatures.

As soon as the upper adsorber group 10, 11, 12, 13 for instance, is loaded by retaining vaporous constituents of the carrier gas, the valves 8 and 23 are closed and the valves 9 and 24 of the lower adsorber group are opened so that the contents of this adsorber group may be loaded. After the valve 31 has been opened, steam coming from the pipe line 32 is conveyed into the adsorber from the top. The vapors so expelled from the adsorption materials are conveyed through the pipe line 34 after the valve 33 has been opened, into a condenser 35, in which the media expelled from the adsorption material may be condensed if occasion arises, together with water.

. It is of advantage to treat the adsorption containers 10, 11, 12, 13 one after the other with steam in the described way and to obtain the expelled vapours preferably in separate fractions.

As soon as the adsorption materials are regenerated, in other words, after the retained media have been expelled therefrom the steam supply is interrupted by operation of a valve 31 and the valve 36 is opened so that the. carrier gas, having been heated up to an increased temperature by the heater 37 can enter the adsorber 10 through the pipe line 39 after the valve 38 has been opened. The at first hot and later on cold carrier gas causes the water within the adsorption materials to be removed and the materials to be dried and cooled so that these materials may be reused for the adsorption of components of the carrier gas. The treatment of the other adsorbers is performed in the same way.

The evaporation in the container 5 is at least continued to such a degree until the remainder contains only the main portion of dicyclo-pentadiene and the benzene fraction or an essential portion of it.

This remainder is conveyed through the pipe line 41 into a still 42 after the valve 40 has been opened. In this still 42 the remainder is fractionated with steam which is led through the pipe line 43. The vapours leave the columns 42 at the top through the pipe line 44 and are conveyed to a condenser 45 from which the condensate can be removed through the line 46 for further use.

The operation of the described plant may be performed as follows:

In the mixer 2 four tons of certain fore-runnings of benzene are mixed with 50 kg. of lime (lime milk). After the solids and the watery solution have been removed the liquid reaches the heater 3, in which the materials are heated to a temperature of 80 C. for four hours. After recooling, the stock is conveyed to the evaporator 5. For five hours cleaned coke oven gas at a temperature of about 15 C. is fed into the evaporator at a rate of 5 cu. m./minute and simultaneously the temperature of the liquid decreases to less than 0 C. caused by the evaporation. The volatile-laden gas is conveyed through the upper adsorber group, each adsorber containing 2.5 tons of activated coal, for two hours and after that through the lower group. Between the different adsorbers the gas is cooled to 15 C. After the gas flow has been interrupted, steam is conducted through each adsorber for one hour and afterwards hot carrier gas C.) for drying purposes and finally old carrier gas for cooling for half an hour are issued into the adsorbers. The remainder in the evaporator is fractionated with steam in the equipment 42. By this mode of op eration the following media are obtained: 3.62 tons of benzene, 2.04 tons of carbon disulphide and 1.44 tons of dicyclo-pentadiene. The yield of benzene, carbon disulphide and dicyclo-pentadiene is based on the use of 10 tons of fore-runnings. The balance of the 10 tons is 2.9 tons of unusable residues.

In practical operation the amount of carrier gas is slowly increased by gases which are contained in the feed stock and escape when the stock is evaporated. This carrier gas surplus is at a suitable point continuously or in certain intervals removed from the recirculating gas flow and in case that cleaned coke oven gas is concerned it may be fed back into the crude gas duct leading to the by product plant.

When the carrier gas loaded with the evaporated constituents is conveyed through several adsorbers, filled for instance with activated coal, a fractionation of the constituents occurs due to the adsorption in such a way that certain constituents gather in certain adsorbers. By treating the dilferent adsorbers individually in order to expel the retained media, pure fractions may be obtained. The adsorber materials and the temperature of the adsorbers should advantageously be chosen in such a way that a fraction of methylcyclo-pentadiene may be obtained from the adsorbers.

Having thus described the present invention so that others skilled in the art may be able to understand and practice the same, I state that what I desire to secure by Letters Patent is defined in what is claimed. WhatI claim is:

1. In the fractionation of fore-runnings obtained in the rectification of crude benzene and comprising substantial amounts of liquid mixtures of dicyclopentadiene, substantial amount of carbon disulfide, some benzene and other vaporizable materials having a boiling point lower than that of dicyclopentadiene, the improvement which comprises vaporizing the lower boiling media in said mixture at a temperature not exceeding 25 C. while retaining the main portion of the dicyclopentadiene in the residue.

2. The method of claim 1 wherein the residue is steam distilled for recovery of the dicyclo-pentadiene.

3. The method of claim 1 wherein the vaporization of said lower boiling media is carried out at a temperature below 0 C.

4. The method of claim 1 wherein the vaporization is carried out under decreasedpre'ssure.

5. The method of claim 1 wherein the vaporization is carried out by contacting said mixture with a carrier gas which is substantially free of water.

6. The method of claim 1 wherein the vaporization is carried out by contacting said mixture with an inert carrier gas which is substantially free of water.

7. The method of claim 6 wherein said inert gas is coke oven gas.

8. The method of claim 1 wherein said mixture is heated, prior to evaporation of said low-boiling media, to a temperature not exceeding 100 C. without substantial evaporation to convert any monocyclo-pentadiene present in said mixture to dicyclo-pentadiene.

9. The method of claim 1 wherein acid constituents in said mixture are eliminated prior to vaporization of said low boiling media by treating said mixture with a member of the group consisting of lime and lime milk.

10. The method of claim 1 wherein the vaporization is carried out by contacting said mixture with an inert carrier gas which is substantially free of water, the vaporized media being subsequently removed from said carrier gas by passage thereof through absorbing media.

11. A method of fractionating the fore-runnings obtained in the rectification of crude benzene, said forerunnings comprising a liquid mixture containing sub stantial amounts of dicyclo-pentadiene, substantial amounts of carbon disulfide, some benzene and other vaporizable materials having a boiling point lower than that of dicyclo-pentadiene, said method comprising the steps of first removing acid constituents from said forerunnings, thereafter heating said fore-runnings to a temperature not exceeding C. to convert any monocyclo-pentadiene present in the mixture to dicyclo-pentadiene, evaporating the lower boiling media from said forerunnings at a temperature not exceeding 25 C. while retaining the main portion of the dicyclo-pentadiene in the residue.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Wilson, The Chemistry and Utilization of Cyclopentadiene, reprinted from Chem. Reviews, vol. 34, Nov. 1, 1944, 49 pages. 

1. IN THE FRACTIONATION OF FORE-RUNNINGS OBTAINED IN THE RECTIFICATION OF CRUDE BENZENE AND COMPRISING SUBSTANTIAL AMOUNTS OF LIQUID MIXTURES OF DICYCLOPENTADIENE, SUBSTANTIAL AMOUNT OF CARBON DISULFIDE, SOME BENZENE AND OTHER VAPORIZABLE MTERIALS HAVING A BOILING POINT LOWER THAN THAT OF DICYCLOPENTADIENE, THE IMPROVEMENT WHICH COMPRISES VAPORIZING THE LOWER BOILING MEDIA IN SAID MIXTURE AT A TEMPERATURE NOT EXCEEDING 25* C. WHILE RETAINING THE MAIN PORTION OF THE DICYCLOPENTADIENE IN THE RESIDUE. 